Shaping of bodies of crystalline carbon



Feb. 21, 1956 COOK SHAPING OF BODIES OF CRYSTALLINE CARBON Filed Oct. 20, 1952 2,735,421 AP Y QF BODIESQF. CR STALLHNECARB j Robin 3 rCooigFioi-ida, Transvaal, ,Hnion of South Africa,

assignon; by mesne assignments; to DiamondAhrasiy/e "Products Limited, JohannesburggT-ransvaal, Union'of South Africa Application .Qctober 20, 195 2, SerialNo. 315,761 Claims priority, 'applicationjGreatBritainOctober 2 2; "1951 13 Claims. (Cl 125-30) :This :invention relates torthe shaping of bodies of crystalline carbon such as diamond; framesite,'stewartite, carbonado and the like.

The shaping ofbodies: of crystalline carbon-by known methods is a lengthy, tedious, diflicult and expensive process calling for the exercise of a specialisfs skill. The

d ect o l, e fec s re nltinefrom:th :;c y lline struc re ma t impossible t re e. he. bodies to spheri al or sp e l shape y. ag indina p r t on l n xsof h i n ce y. toscarry out an. init al rutipg p ration befor It is obviousthat 01 ntr au ldiifieu t a process 118 -s. arce1y-teconomi w n; d li g .withsmafl. bodies. audi -indeed DldiE ;-b

. rtain siz nnotbe h shandled. At thecame. tim

there exists a greater dem and ,forv industrialqpurposes if r bo ies of..roundedshapetbann an e LSfiIiSfidL by -..bot s whi h arercuudwhen won. present invention is to provide a The object of the method and means of rounding such bodies which is very much more rapid, certain and inexpensive than can be achieved by known methods and which can be used to round bodies too small to be handled or to be handled economically by existing methods.

The method of the invention consists in centrifuging one, and preferably a number, of bodies in contact with a circumferential wall at least the surface of which is composed of hard metal.

The term hard metal includes carbides, nitrides as hard metals.

On the face of it, centrifuging of these bodies in contact with an abrasive surface would appear to offer no practical possibility of producing a rounded body, because the haphazard presentation of the faces to the surface would seem to be the exact equivalent of a haphazard presentation of such a body to a lapping wheel; a procedure which persons skilled in the art know to be sterile.

It is, therefore, a matter of considerable surprise that the method of the invention does in fact produce rounded bodies; and applicant can only explain this unexpected result by assuming that the process must in fact be a species of bruting process in which the bodies are rounded by impact against the wall and possibly also against one another; and that if grinding does take place it is a secondary operation.

Whatever the reason, however, it is the case that bodies treated according to the invention are rounded rapidly to a degree which enhances their commercial value very substantially.

The method of the invention consists further in confining a body and preferably a number of bodies within a cylindrical space bounded by a circumferential wall as above specified, injecting pressure fluid into the space to centrifuge the body or bodies; and recovering, from fluid discharged from the space, detritus entrained in the fluid. Preferably the fluid is atmospheric air or a gas.

when used in this specification and the like commonly classed nited States Patent 0.

r 2,735,421 r atented 9:.

:2 sApparatusvfor: putting the method .to .use;.,consists.-in-. a

; cylindrical casing the. surface. layers attleast .OflhflzjfiilCllIIlferential wall of which are composed:wholly-eorxpre- ;.ponderantly of; hardmetaL- 311163118: of accessefor intro- 5 duction: OfnIQHgh'u bodies; .and. means =to-1 inject; pressure fluid and; preferably, air or gas, substantially: tangentially into, the casing.

. 'AmembOdimentof: apparatus .,according towthe :invention isqillnstrated iinythesaccompanying drawingsain l0..which- Figure "section;

Figure Figure .:wall;=. and

5 Eigure.4;isan elevationof a circumferential wall.

The-apparatus illustrated 1 in "Figures 1 ,;and ,2; consists in: a;massive.-block ,5; for example made of'brass, with a cylindrical recess; 6. ;;In; the :recess: 6 -there,;are -housed 20. -.in; 5the: direction' -from the base 11: of ithfi' recess, towards its mouth 12, a washer '7, a ring 8, a Washer.=9.;1and; a .5 gasket 10. ;'The;washers'7 and91 andithe ring 8 are made of cemented tungsten-clanbide. =A co.ver;;plate.24;.holds the assemblyin-the recess.

The base 11 of the recess is provided withan axial saperturej, 13;;Wbich isriittedlwitht aawire gauze screen 14. An axial tube 15 extends from the cover plate 241m the 1-.-.-sereen:14. Thea nbei:15-.-is provide awitbnerforations 1 gat-thelevel ofthegringlg.

zlmpretide ae essto. the ea si stzl definedibetweenrth arias; andiheitubenfiQthe datterei att ched-t n a screw head 17 which screws into the cover plate 24.

The circumferential wall of the recess 6 is provided with an annular groove 18 from which leads a passage 19 opening into a coupling 29. Communication between the groove 18 and the cavity 21 is by means of an injecting hole 22 which is substantially tangential to the inner circumference of the ring 8.

In use, the cavity 21 is charged with a number of bodies to be treated by unscrewing the head 17. After the cavity has been charged the head is replaced. The coupling 20 is connected to a source of compressed air. The air passes along the passage 19 into the groove 18 and through the tangential hole 22 into the cavity 21. It will be seen that the air subjects the bodies to a centrifuging action in the cylindrical space provided by the cavity 21 and bounded by a circumferential wall provided by the ring 8.

The air passes through the perforations 16 into the tube 15 and through the screen 14. Air escaping through the screen 14 is filtered or otherwise treated for the recovery of entrained detritus.

The ring 8 is made of a very fine grained cemented tungsten carbide to achieve the most lasting qualities.

However, applicant anticipates that the carbide grade will vary with the size of the bodies being treated. With bodies of minus 9 plus 10 mesh Tyler applicant has found that an air pressure of between 17 and 19 pounds per square inch gives the best results.

In Figure 3 a modified form of ring St: has been illustrated. In this ring there are two injecting holes 22a and 22b side by side. This construction minimizes the concentration of the jet of air and consequently lessens the Wear on the zone 23 of the ring 8a opposite the holes 5 22a and 22b.

In Figure 4 two holes 220 and 22d are illustrated at opposite ends of the ring 8b. The holes 220 and 22d enter the cavity 21 in the same rotational sense. The term gem stones used in the appended claims is intended to include stones used for industrial purposes.

I claim: 1. An apparatus for shaping bodies of crystalline car- 1 is an elevation of-gtheg apparatuszrrnostlygin 2 is a section on the.;line;.2.2';ofEigure1 1; 3 isra perspective view: of; a :circumferential into the casing, and a tubular member positioned axially of the cylindrical casing to provide an outlet for said fluid from the casing.

2. The apparatus claimed in claim 1 in which the wall consists in a ring of cemented tungsten carbide.

3. The apparatus claimed in claim 1 in which the wall consists in a ring of cemented tungsten carbide pierced by at least one passage opening out substantially tangentially to the inner circumference of the ring.

4. The apparatus claimed in claim 3 including two jets in the same tangent plane.

5. The apparatus claimed in claim 3 including two jets on parallel tangent planes.

6. A method of shaping crystalline carbon gem stones consisting in charging the stones into a cylindrical space bounded by a circumferential Wall at least the surface of which is composed of hard metal, substantially tangentially injecting pressure fluid into the space to repeatedly circulate the stones circumferentially of the space and to centrifuge the stones and discharging the fluid axially of the space.

7. A method according to claim 6 in which the hard metal is cemented tungsten carbide.

8. A method according to claim 6 in which the fluid is a gas.

9. A method according to claim 6 in which the fluid 18 air.

10. A method of shaping crystalline carbon gem stones comprising charging said stones into a cylindrical space, and subjecting the stones to the action of a high pressure fluid jet while the stones are in the cylindrical space to drive them circumferentially within the space and repeatedly circulate them relative to and in contact with a stationary circumferential hard metal wall completely surrounding the space.

11. The method as set forth in claim 10 wherein the fluid pressure is about 19 lbs/sq. inch and is introduced tangentially into the cylindrical space.

12. A method of shaping crystalline carbon gem stones comprising charging the stones into an annular space bounded by a wall the surface of which is composed of hard metal, subjecting said stones to a jet of high pressure fluid to repeatedly circulate the bodies circumferentially of the space and discharging the fluid axially of the space.

13. A method of shaping crystalline carbon gem stones comprising confining said stones Within a closed cylin-. drical space the circumferential wall of which is composed of hard metal, injecting a jet of high pressure fluid through a small opening in the circumferential Wall to subject said stones to repeated circulation in the cylindrical space in contact with each other and with the cylindrical wall, and discharging the fluid axially of the space.

References Cited in the file of this patent UNITED STATES PATENTS 860,404 Moussette July 16, 1907 1,508,345 Lupo Sept. 9, 1924 1,549,615 Schroter Aug. 11, 1925 1,590,655 Spicer June 29, 1926 1,647,249 Podszus Nov. 1, 1927 2,041,346 Jaques May 19, 1936 2,123,635 Moore July 12, 1938 2,175,457 Dunn Oct. 10, 1939 2,242,901 Birch May 20, 1941 2,566,103 Weston Apr. 28, 1951 2,612,889 Heyman Oct. 7, 1952 

1. AN APPARATUS FOR SHAPING BODIES OF CRYSTALLINE CARBON COMPRISING A CYLINDRICAL CASING HAVING ITS INNER WALL COMPOSED OF HARD METAL, ACCESS MEANS AT THE TOP PORTION OF THE CASING FOR INTRODUCING SAID BODIES INTO SAID CASING, MEANS FOR INJECTING A JET OF HIGH PRESSURE FLUID TANGENTIALLY INTO THE CASING, AND A TUBULAR MEMBER POSITIONED AXIALLY OF THE CYLINDRICAL CASING TO PROVIDE AN OUTLET FOR SAID FLUID FROM THE CASING. 